1862.] JAMIESON — GLACIATION OF SCOTLAND. 165 



embankment of the uppermost of these three lakes gave way, and 

 its water, rushing into the next one, caused it also to burst its bar- 

 rier ; and the contents of both, now descending suddenly into the 

 lowermost lake, broke the embankment of it likewise ; so that the 

 contents of the whole three were at once let loose, and rushed down 

 the steep channel of a mountain- stream with immense force. Owing, 

 luckily, to the retired, barren nature of the locality, there were no 

 houses in the way, nor much else that could sustain serious damage, 

 except the canal, a gTcat part of which was destroyed, and quite filled 

 up with stones and gravel. It took an expenditure of several thou- 

 sand pounds to repair the injury done to its channel, and the engi- 

 neer who superintended the work told me that some of the boulders 

 he had taken out of it weighed eleven tons. Here, then, was a great 

 volume of water rushing violently down the flank of a hill, through 

 a descent of about 700 feet, and carrying along with it stony debris 

 and boulders of several tons weight. Having seen some account of 

 the matter in the newspapers at the time, I was very glad when, in 

 August 1860, I had an opportunity of examining the scene of the 

 catastrophe. By this time the damage to the canal had been re- 

 paired, but the channel of the hill-stream was very much as the 

 torrent had left it. The rocks there consist of frequent alternations 

 of clay-slate, greywacke-grit, and syenitic greenstone, covered occa- 

 sionally by a variable thickness of stony earth or drift. This cover- 

 ing the rush of water had in many places quite cleaned off, carrying 

 the boulders and stony debris before it, and throwing them down in 

 those spots where the force of the torrent began to fail. I saw many 

 blocks that it had borne along, measuring 3 to 4 feet in length, and 

 a few even from 8 to 11 feet. On none of these was there anything 

 at all resembling the glacial polish and striae ; neither were there 

 any such markings on the smaller pebbles. Moreover, the debris 

 was for the most part quite unmixed with clay or mud, and consisted 

 either of clusters of large boulders, or masses of washed gravel, — the 

 finer sediment having been carried away by the retiring water. This 

 debris was therefore quite unlike our boulder- earth, and more resem- 

 bled some of the coarser kinds of what I have elsewhere described 

 as the upper roUed gravel that is so frequently met with covering the 

 drift in almost aU our river- valleys. I also examined the rocks 

 along the bottom and sides of the ravine, to see how they were 

 affected. Now, its direction is right down the hill- slope from S.W. 

 to N.E., with occasional windings, and such was the course of the 

 torrent in descending it ; but here there was a circumstance which 

 added greatly to the interest of the case. This was the occurrence of 

 true glacial striae and scores, beautifully and extensively marked, and 

 nmning obliquely across, and sometimes even at right angles to the 

 direction of the ravine ; so that there could be no risk of confound- 

 ing them with any ruts made by the descending torrent, which by 

 washing off the drift had finely exposed these markings, and they 

 could be traced passing under banks of undisturbed drift. These 

 glacial impressions, I may also mention, are not confined to this 

 ravine, but are displayed over much of the neighbourhood, and will 



